Search systems use query revision engines to revise search queries, for example to include substitute terms (e.g., synonyms) of query terms. To identify a substitute term for a query term, query revisers evaluate candidate substitute terms according to various criteria, such as criteria that estimate whether, in a particular context, a candidate substitute term is a good synonym of the query term. Once search results are obtained using revised search queries, a scoring engine may then score search results based on an assumption that all occurrences of all substitute terms for a query term are equally weighted. In other words, the scoring engine may ignore the context of the substitute terms.